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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Precision Agriculture Technology Evaluation using Combined AHP and GRA for Data Acquisition in Apiculture</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Jorge Ivan Romero-Gelvez</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Sandra Viviana Beltrán-Fernández</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Andres Julian Aristizabal</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Sebastian Zapata</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Monica Castañeda</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Universidad de Bogotá Jorge Tadeo Lozano</institution>
          ,
          <addr-line>Bogotá</addr-line>
          ,
          <country country="CO">Colombia</country>
        </aff>
      </contrib-group>
      <fpage>135</fpage>
      <lpage>145</lpage>
      <abstract>
        <p>Precision Agriculture has been experiencing an essential growth in the implementation of industrial internet of things based applications. The proposed evaluation framework uses a hybrid decision-making model for technology selection. The structure combines two extensively used methods, Analytic hierarchy Process (AHP) and Grey Relational Analysis (GRA). The evaluation process of data acquisition system features is two-fold. First, AHP is used to assign importance to the criteria. Next, GRA is used to assess the alternatives concerning the criteria. Finally, we obtain the final grey relational coeficients for each alternative and chose the most suitable one.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Precision Agriculture</kwd>
        <kwd>Apiculture</kwd>
        <kwd>AHP</kwd>
        <kwd>GRA</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>plants, categorize them and predict yield and crop load [7], the collection of large data sets for
a single corn plant [8], enhance energy eficiency [9], remote sensing using drones [10], climate
change monitoring [11], detection of infections and crop classification [12], smart crop-field
monitoring and automation of irrigation systems [13], the use of IoT devices for sensing the
agricultural data and store data into the Cloud [14], the use of Data Mining Techniques and IOT
to improve the crop yield [15], nutrient management for livestock [16, 17] and pollution-free
cultivation systems among many others.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Literature review</title>
      <p>Analytic hierarchy process is a decision-making tool whose main objective is to interpret the
intangible judgments of people as tacit preferences. It does so by decomposing the problem into
several hierarchical levels. The first level is the objective or goal, next, the comparison criteria
and sub-criteria, and at last, the alternatives [18]. Using AHP brings advantages such as
handling uncertain information lowering the experience of decision-makers. The AHP technique
can be applied in many fields. Among them, we can highlight project selection,
prioritization of environmental impacts[19], mining method selection [? 20], budget allocation, medical
decision-making, transportation [21], manufacturing an supply chain [22, 23, 24] among many
others.</p>
      <p>
        Grey relation analysis is applied in multiple fields. Yeh [25] proposed an early combination
with multi-criteria decision-making techniques in order to evaluate weapons systems. Later,
other developments arise combining GRA with AHP in diverse areas including the selection of
marketing networks [26], the impact analysis of damage in natural disasters [27] among others.
A formal description of GRA and AHP is given by [28]; later Song and Jamalipour[29, 30, 31]
extend the use of the AHP-GRA combination in the selection of networks in wireless
communications, the same year Li also applies this combination in the selection of materials [32] and
data transmission on demand. Zhang also implemented this combination in the evaluation of
knowledge management tools [
        <xref ref-type="bibr" rid="ref5">33</xref>
        ], Han managed to apply this combination in maintenance
[
        <xref ref-type="bibr" rid="ref6">34</xref>
        ] and Zhang in the optimization of the wastewater treatment process [
        <xref ref-type="bibr" rid="ref7">35</xref>
        ]. Zhao in the
evaluation of courses [
        <xref ref-type="bibr" rid="ref8">36</xref>
        ]. [
        <xref ref-type="bibr" rid="ref9">37</xref>
        ] natural gas pipeline operation schemes, [
        <xref ref-type="bibr" rid="ref10">38</xref>
        ] Evaluation of tea
crops [
        <xref ref-type="bibr" rid="ref11">39</xref>
        ] supplier evaluation More recent applications in agriculture that include the
AHPGRA combination can be seen at [
        <xref ref-type="bibr" rid="ref12 ref13 ref14 ref15 ref16">40, 41, 42, 43, 44</xref>
        ].
      </p>
      <sec id="sec-2-1">
        <title>2.1. Analytic hierarchy process</title>
        <p>
          For solving the Decision Making problem, we propose the use of AHP, as an accepted and used
often in problems that include subjective judgments of people. According to Saaty [
          <xref ref-type="bibr" rid="ref17">45, 18</xref>
          ]
the AHP is a useful tool to structure complex problems that influence multiple criteria and
at the same time classify a set of alternatives in order of importance. Initially a hierarchical
structure is made where the main decision problem is identified, then the criteria and
subcriteria that are taken into account for the decision are identified.The last level corresponds to
the set of alternatives that will be evaluated concerning each of the criteria and sub-criteria.
This evaluation is carried out through a series of binary comparisons in a matrix n x n, where n
is the number of elements to be compared. In order to make the comparison, a scale is required.
to find the relative priorities of the criteria and / or the alternatives. This step is based on the
eigenvector theory. For example if a comparison matrix is A, then:
 ′ = ⎢  2′1
⎡  1′1
⎢
⎢
        </p>
        <p>⋮
⎣⎢   ′ 1   ′ 2
 1′2
 2′2</p>
        <p>⋮
⋯</p>
        <p>⋮ ⎥
⋯   ′ ⎥
⎦</p>
        <p>Where w corresponds to the column vector of the relative weights obtained by making the
average of each line of the normalized comparison matrix.
tion of the original comparison matrix with the column vector of relative weights.</p>
        <p>The value of  max is obtained by adding the column vector corresponding to the
multiplicaBecause comparisons are made subjectively, a consistency index is required to measure the
consistency of the person making the ratings. The consistency index and the consistency ratio
CR are calculated as follows:</p>
        <p>=  max
 max = ∑ 



=
 max − 
 − 1

=</p>
        <p>Where the RI inconsistency ratio is a comparison constant that depends on the size of the
paired comparison matrix for sizes of n = 9 (our criteria x criteria matrix) RI = 1.45</p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. Grey Relational Analysis</title>
        <p>comparable, the 
pressed as   ′ = (  ′1,   ′2, … ,   ′ ), where   ′ means the ℎ</p>
        <p>
          comparative factors can be expressed as:
Grey relational space theory introduced by Deng Julong [
          <xref ref-type="bibr" rid="ref18">46</xref>
          ] is widely used to obtain the
relations among the reference factors and other associated factors in a system.
        </p>
        <p>Step 1. Generate the comparative factors. A set with  components of criteria can be
excriteria of   ′ . If all criteria are
(1)
(2)
(3)
(4)
is defined as follows (6):
• In case of ‘smaller-is-better’ data treatment   ( ), can be normalized into  ∗( ) The formula
Step 3. Compute the distance Δ0 ( ) between the reference series and the comparative series.
 = 0.5.
risk factor   , which is given as follows:
where Δmin = min min (Δ ) ,</p>
        <p>
          Δmax = max max (Δ ) , and  is an identifier 
afecting the relative value of risk without changing the priority. According to [
          <xref ref-type="bibr" rid="ref18">46</xref>
          ] generally
∈ (0, 1) only
        </p>
        <p>Step 5. Calculate the degree of grey relation based upon the   and the group weights of
Step 2. Determine the reference series and normalize all data sets. Degree of relation can
represent the relation of two series; therefore, an objective series called reference series shall
the following types: ‘larger-is-better’ or ‘smaller-is-better’.
be established and expressed as 0 = ( 01,  02, … ,  0 ). Data sets can be treated using one of
is defined as follows (5):
• In case of ‘larger-is-better’ data treatment   ( ), can be normalized into  ∗( ) The formula
(5)
(6)
(7)
(8)
(9)
where Δ
Step 4. Ca=lcu‖‖ la0te−the ‖‖g.rey relational coeficient   as follows:
  =
Δmin +  Δmax
Δ +  Δmax</p>
        <p>,  = 1, 2, … ,  ;  = 1, 2, … ,</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Methodology for combined AHP and GRA in Apiculture</title>
      <p>In this section we show how the use of a model that combines AHP-GRA can help to manage
qualitative and quantitative information in the selection of technology for data acquisition for
the beekeeping sector. Beekeeping has particular characteristics necessary for proper
performance of its hives, such as location, temperature, humidity, population control of the swarms,
among others. The model was developed for a case in Colombia, located in the rural area of
Carmen de Carupa. Which has a relative humidity of 86% and an average temperature of 10
 ∗( ) =</p>
      <p>( ) − min   ( )
max   ( ) − min   ( )
 ∗( ) =</p>
      <p>max   ( ) −   ( )
max   ( ) − min   ( )</p>
      <p>⋮ ⎥
degrees Celsius. Next we will describe the Smart farming technologies, then we will describe
the alternatives and the criteria of the model, finally we will apply the AHP-GRA combination
in order to obtain the best alternative for the selection of data acquisition technology.</p>
      <p>Smart farming technologies are classified into three principal classes that incorporate entire
operation of Precision Agriculture:
• Data acquisition technologies: this class includes all surveying, mapping, navigation and
sensing technologies.
• Data analysis and evaluation technologies: this class includes from computer-based
decision models to complex farm management and information systems.</p>
      <p>• Precision application technologies: this class contains all application technologies.
In order to evaluate data acquisition technologies. First, we determine alternatives and criteria
from an extensive literature survey, next we apply AHP in order to obtain the weights for all
criteria. At last, we apply grey relational analysis to rank all alternatives and select the most
suitable one. An schema of the evaluation process can be seen in Fig. 1 as follows:</p>
      <sec id="sec-3-1">
        <title>3.1. Technology Alternatives for Precision Agriculture</title>
        <p>• Global Navigation Satellite Systems: is the conventional name for satellite navigation
systems that contribute independent geo-spatial positioning with global coverage.
• LiDAR Sensors: Light Detection and Ranging are instruments that measure the
distance from the target by laser.</p>
        <p>• Thermal Cameras Systems: Thermal cameras have the ability to generate images
related to the ambient temperature.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Evaluation Criteria</title>
        <p>Many factors need to be considered in the selection of perception sensors and other
technologies in agriculture, which are described below:
• Easy Maintenance: Reliability is essential for perception-based applications. Sensor
performance will quickly degrade when exposed to harsh agricultural environments,
and frequent sensor maintenance is required. The ease of sensor maintenance is another
consideration in selecting a perception sensor.
• Low Cost: The cost is one of the most important factors that influence, since in some
cases the farmer cannot have access to high-cost elements that allow him to follow up
on bees or any type of food that he sows on his farm.
• Easy to Use: The simple and fast use of the measuring instruments used in Precision
Agriculture is essential when acquiring them, since some farmers do not know how to
read or write, therefore a friendly technology is needed for them.</p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. AHP hierarchy and determination of relative weights of all criteria</title>
        <p>From the literature review, the alternatives and criteria most related to our case study are
established and we build the hierarchy that can be seen in the figure 2 as follows.</p>
        <p>AHP is used to determine the relative weight of each criterion. using the scale from 1 to
9 with diferent levels of importance proposed by saaty. The priorities are calculated by
calculating the dominant eigenvector that belongs to the matrix of pairwise comparisons for the
criteria. The consistency ratio of the matrix of even comparisons corresponding to the criteria
is CR=0.06239. Te weights of all criteria can be seen in Table 2 as follows.</p>
      </sec>
      <sec id="sec-3-4">
        <title>3.4. Usage of GRA to establish the best technology for data acquisition</title>
        <p>The qualitative and quantitative evaluations are added in the table below, the criteria  = {1, 2}
are qualitative. On the other hand, the criterion  = 5 is quantitative and corresponds to the
price in dollars of each item.</p>
        <p>Step 1. Generate the referential series and the compared series.
Step 2. Then the referential series of  0 = {6, 8, 100}, and the compared series of  1 = {2, 4, 100},
 2 = {6, 5, 300}, and  3 = {6, 8, 150}.</p>
        <p>Step 3. Calculate the distance between the referential series and the compared series.
Γ01(Lidar) = 0.387303333,
Γ02(Thermal − cameras) = 0.832982667, Γ02(GPS) = 0.973003333 The priorities of the three
potential technologies (in order with their grey relational grades) is GPS &gt; Thermal cameras &gt;
Lidars.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Conclusions</title>
      <p>In this article, the combined AHP and GRA procedure gives a solution, including quantitative
and qualitative information. This coordinated approach has selected the technology based on
the proposed evaluation model. The benefit with this approach is that it is quite adapted to
deal with problems that involve qualitative and quantitative values, and enables the evaluation
based on limited information.</p>
      <p>Based on the result obtained in the model, we can conclude that the best technology to
acquire data in apiculture is GPS. It will help to obtain a useful mapping of the terrain with
an adequate angle and temperature for giving the right conditions to the development of bees
population.
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